Vertical axis wind turbine

ABSTRACT

A vertical axis wind turbine formed from an arrangement of fixed stator blades to provide fluid flow acceleration into an arrangement of rotatable blades secured to a generator for invoking electrical power generation. The stator blades are maintained in position by use of a stator plate. Rotor blades are coupled to the generator. The amount of stator and rotor blades may be scaled in number and size depending upon the type of generator to be driven and associated mechanical energy to be obtained. The stator blades are designed for air deflection in a direction for optimal rotor blade rotation by accelerating air flow into a pre-swirl before the flow contacts the rotor blades. Each stator blade is oriented at a sufficient stagger angle so that an angle of the relative velocity does not exceed the stall angle of said rotor blade.

PRIORITY CLAIM

In accordance with 37 C.F.R. 1.76, a claim of priority is included in anApplication Data Sheet filed concurrently herewith. Accordingly, thepresent invention claims priority as a continuation of U.S. patentapplication Ser. No. 14/703,471, entitled “Vertical Axis Wind Turbine”,filed on May 4, 2015, which is a continuation of U.S. patent applicationSer. No. 13/648,896, entitled “Vertical Axis Wind Turbine”, filed onOct. 10, 2012, now U.S. Pat. No. 9,022,721, issued on May 5, 2015, whichclaims priority to U.S. Provisional Patent Application No. 61/545,424,entitled “Vertical Axis Wind Turbine”, filed on Oct. 10, 2011, thecontents of which are incorporated herein by reference in theirentirety.

FIELD OF THE INVENTION

The present invention relates to the field of wind turbines and moreparticularly to a vertical axis wind turbine having a concentricarrangement of fixed blades for deflecting wind forces for wind flowacceleration.

BACKGROUND OF THE INVENTION

Conventional wind turbines operate on the energy of the wind to turn twoor three propeller-like blades around a rotor. The rotor is connected toeither a vertical or horizontal shaft mounted generator that spins togenerate electricity. Wind turbines are preferably mounted on a tower orbuilding structure so as to capture the most energy in a location so asto receive the full effects of the wind yet not disturb the immediateenvironment. Typically wind turbines are positioned about thirty meters(30 m) above the ground where they can take advantage of winds that arenot affected by ground effect obstructions. Wind turbines consistgenerally of blades that spin with respect to two orientations,vertically orientated axis or horizontally orientated axis.

Wind energy is fueled from the kinetic energy of the wind, making wind aclean fuel source. Wind energy will not pollute the air like powerplants that rely on combustion of fossil fuels, such as coal or naturalgas. Wind turbines that rotate about a horizontal axis are best suitedfor large unobstructed areas hence the creation of the wind farms.Vertically disposed wind turbines are well suited for congested areas,such as residential neighborhoods.

Wind power must compete with conventional generation sources on a costbasis. Depending on how energetic a wind site is, the wind farm may ormay not be cost competitive. Even though the cost of wind power hasdecreased dramatically in the past ten (10) years, the technology stillrequires a higher initial investment than fossil-fueled generators asthey typically operate at ten percent (10%) efficiency.

Further, although wind power plants have relatively little impact on theenvironment compared to other conventional power plants, there is someconcern over the noise produced by the rotor blades, aesthetic (visual)impacts, and sometimes birds that have been killed by flying into therotors of horizontal placed axis.

The need for renewable energy sources is constantly increasing. A focuson improved wind turbines has steadily increased over time. The generalquandary with wind turbines to date relates to the inefficient transferof kinetic energy to mechanical energy for power generation. Aconventional wind turbine converts as little as ten percent (10%) of thepossible kinetic energy into mechanical energy for electricitygeneration due to the many factors that affect the efficiency of aconventional wind turbine.

What is lacking in the art is a vertical axis wind turbine designcapable of producing a wind turbine capable of improving upon theefficiencies necessary to convert a higher amount of kinetic energy intomechanical energy. The instant invention addresses these and othershortcomings by introducing a vertically aligned wind turbine powergenerator having improved rotor and stator blade geometry.

SUMMARY OF THE INVENTION

Disclosed is an improved fluid turbine formed from a concentricarrangement of fixed stator blades having an optimal geometric formationto provide fluid flow acceleration into a concentric arrangement ofrotatable blades having a geometric formation for rotating to invokeelectrical power generation. In a basic configuration, the turbine ofthe instant invention has at least three stator blades and at least tworotor blades for the direction of air. The amount of stator and rotorblades may be scaled in number and size depending upon the type ofgenerator to be driven and associated mechanical energy to be obtained.The turbine preferably has a vertical axis for deflecting airacceleration into a rotatable rotor blade assembly that is coupled to agenerator to invoke electrical power generation. The stator blades aredesigned for air deflection in a direction for optimal rotor bladerotation by accelerating air flow into a pre-swirl before the flowcontacts the rotor blades. The rotor blades output the power by turningflow with a large angle for rotation of a generator.

Accordingly, it is an objective of the instant invention to provide awind turbine having stator and rotor blades of a geometric formationthat provide for greater efficiencies over a conventional vertical axiswind turbine, the wind turbine having a vertical axis that allows for asmaller footprint, reduced noise, and an omni-directional(axis-symmetric) design to allow wind from any direction to be captured.

It is a further objective of the instant invention to encase the rotorassembly within the stator assembly so that only two bearings are neededand constitute the only mechanical rotating parts of the assembly.

It is a further objective of the instant invention to strategicallyposition stator blades to accelerate the airflow by passage areareduction.

It is a further objective of the instant invention to strategicallyposition stator blades to generate pre-swirl of the flow, which is toguide the flow to tangential direction in the direction of rotorrotation instead of keeping the flow in the radial direction before theflow hits the rotor.

Yet still a further objective of the instant invention is to disclosethe use of stator blades that are oriented at a sufficient stagger angleso that an angle of the relative velocity does not exceed the stallangle of a rotor blade.

It is a still further objective of the invention to provide a pluralityof stator blades for engaging an incoming wind flow. The wind flow mayinclude, inter alia, wind, air water or the like fluid flow containingkinetic energy for conversion to mechanical energy for use in powergeneration.

It is a further objective of the instant invention to use the statorleading edges as a support for an optional mesh/screen to preventinjuries and protect the invention from unwanted objects in theproximity of the rotor assembly.

It is another objective of the instant invention to provide a pluralityof rotor blades rotatably coupled that have an increased rotor turningangle capable of improved efficiency.

Other objectives and advantages of this invention will become apparentfrom the following description taken in conjunction with anyaccompanying drawings wherein are set forth, by way of illustration andexample, certain embodiments of this invention. Any drawings containedherein constitute a part of this specification and include exemplaryembodiments of the present invention and illustrate various objects andfeatures thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a perspective view of a vertical axis wind turbineaccording to an embodiment of the instant invention;

FIG. 2 depicts a cross sectional perspective view thereof;

FIG. 3 depicts a cross sectional top view thereof;

FIG. 4 is a graphical illustration of the relative position between astator blade and a rotor blade;

FIG. 5 is a graphical illustration of a pre-swirl of the incoming windobtained from stator blade; and

FIG. 6 depicts definition about a blade.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the Figures in cooperation with the description,specific embodiments shall be presented exemplifying the invention andbest mode known at the time of presentation.

FIGS. 1-3 illustrate a graphic orientation of a perspective of avertical axis wind turbine 10. Stator blades 12 having a predefinedgeometry are positioned for guiding wind flows and velocities for use inspinning rotor blades 14. The rotor blades coupled to a centrallydisposed vertical axis generator (not shown), the rotation of the rotorblades causing rotation of the generator to permit the generation ofpower. The wind turbine includes a number of fixed stator blades 12 anda number of rotor blades 14 for rotating about a vertical axis. Thestator is arranged in a concentric arrangement of fixed stator blades 12to condition and accelerate the incoming wind. It should be noted thatthe stator blades may be additionally capable of conditioning andaccelerating gas, water or other fluid flows but for purposes ofsimplicity all embodiments within this disclosure will be based upon thecollection of wind energy. The turning edge of each stator blade 12 isshaped to deflect the wind into the rotating direction of the rotorblades 14. The stator assemblage provides structural integrity about thesystem. Each stator blade 12 having a leading edge 16 and a trailingedge 18; a pressure surface 20 shaped concavely from a leading edge to atrailing edge, and an upper surface 22 shaped convexly from the leadingedge 16 to the trailing edge 18.

The turbine assembly is preferably made from carbon fiber or the likelight weight durable composite. The embodiment depicted has eightstationary stator blades and three rotor blades. The stationary statorblades 12 are about 30″ tall and consist of a 0.02″ thick shell withopen ends. Armored end caps are bonded into each open end and a securingfilm is placed on the trailing edge 18. Each stator blade 12 receives acoating that is a UV protectant and made to a smooth shiny surface freeof orange peel.

Stationary blade end plates (24, 26) have a diameter of about 26″(inches). The lower plate 24 has about a 0.075″ thickness and the upperplate 26 about 0.185″ thickness. Each plate receives a coating that is aUV protectant and made to a smooth shiny surface free of orange peel.Low friction sealed bearing housing 28 allows the rotor blade assemblyto rotate freely. In a preferred embodiment, each plate includes a hubfor attachment and cutouts as needed to access hardware. The cutouts donot affect the top-level wind turbine assembly structurally by static ordynamic forces and personnel are protected from flying components. Thebearing housings described herein can be ball bearing or magneticbearing. Unique to this invention is that the bearings are the onlymechanical rotating part on the assembly.

The rotor blades 14 are about 28″ tall and consist of a 0.02″ thickshell with open ends. Each blade 14 has a leading edge 30 and a trailingedge 32. Armored end caps are bonded into each open end and a securingfilm is placed on the trailing edge 32. Each rotor blade 14 receives acoating that is a UV protectant and made to a smooth shiny surface freeof orange peel. Each rotor blade 14 has a upper surface 31 and a lowersurface 33.

FIGS. 4-6 depicts the stator and rotary blade design including the chordline, camber line and stagger angle. Each stator blade 12 is orientedsuch that a sufficient stagger angle 58 exists between a first line 62passing perpendicular from the leading edge 16 of the stator blade tothe center of a vertical axis 60 and a second line 50 passing from saidleading edge 16 of the stator blade 12 to the trailing edge 18 of saidstator blade 12. The stagger angle 58 is positioned so that an angle ofthe relative velocity does not exceed the stall angle, between −50° and50°, of the rotor blade. Each stator blade includes a turning anglebetween two tangential lines at the leading edge 16 and trailing edge 18of the meanline between zero to ninety degrees.

The rotor assembly is a concentric arrangement of rotatable rotor blades14 within the stator inner radius. The rotor blades 14 are designed toforce the air into a large turning angle. The stator blade 12 and rotorblade 14 assembly can be scaled up in size or quantity, or both andinclude an unlimited number ‘_(n1)’ of stator blades and may include anunlimited number ‘_(n2)’ of rotor blades. The positioning of the blades,and the quantity thereof, can be positioned in relation to the wind. Awind can have a positive incidence value between stator openings, or anegative incidence value. A three rotor assembly may have one rotor atany given time in positive position with the wind, with eight statorblades for conditioning the wind. A six rotor blade assembly may havetwo rotors at any given time in positive position with the wind. Athirteen rotor blade assembly may have four rotors at any given time inpositive position with the wind. Each rotor blade includes a turningangle between two tangential lines at the leading edge and trailing edgeof the meanline between zero and one hundred fifty degrees.

Rotary blade end plates are defined as an upper plate 34 and a lowerplate 36, each plate has about 20.03″ diameter and each plate has abouta 0.075″ thickness. The plates receive a coating that includes a UVprotectant and made to a smooth shiny surface free of orange peel. Thelow friction sealed bearing housing 28 is attached to the upper plate34. The turbine assembly mounting surface shall mount to the generatoradaptor so as to minimize mount flex to no more than 0.01″(+0.01″/−0.01″). A low friction sealed bearing housing 36 is attached tothe lower plate 37 in combination with the stator lower plate 24.Generator to turbine assembly interface consists of a male shaft 38 froma generator which is coupled to the turbine by use of a female coupling.The male and female patterns act as a key for transmitting rotary torquefrom the turbine to a generator. One shaft shall be secured using a setcrew to the female coupling. The other shaft will float freely.

The chord line 50 is the straight line drawn from the leading edge (LE)52 to a trailing edge (TE) 54. To quantify camber line 56, a curved linedrawn from the leading edge 52 to the trailing edge 54 staying alwayshalfway between the upper surface and the lower surface would equal themean camber line 56. The maximum difference between this and the chordline 50 is the amount of camber line 56 and can also be expressed as adistance or as a percentage of the chord length. The method used tooptimize the angles provide for the use of airfoil design within thestator/rotor combination for purposes of maximizing the expected meanpower energy potential of the wind. Aerodynamic flow depends on thepitch angle and blade optimization comprise chord and twistdetermination along the blade axis. Each blade has an airfoil shape,chord length and camber line to define the angle. The (LE) 52 is aportion of the blade facing the incoming wind and a blade (TE) 54 is thetail end of the blade. The chord line 50 is orientated in a straightline connecting the (LE) and (TE) while the camber line 56 is orientatedin a curved line connecting the (LE) 52 and (TE) 54 defining the camberof the blade, pitch 56 orientated is the (LE) 52 to (LE′) 52′ distancebetween two adjacent blades, turning angle is the deflection anglebetween the (LE) 52 and (TE) 54 camber lines, stagger angle 58 that isthe angle between the blade chord line 50 and the turbine radius,incidence angle is the angle between incoming wind and camber line 56,and solidity is the ratio of chord divided by pitch.

Blade leading portion of the blade facing the incoming flow. edge (LE)Blade trailing tail end of the blade. edge (TE) Chord line straight lineconnecting the LE and TE. Camber line The meanline or the center line ofthe airfoil connecting the LE and TE and defining the camber of theblade. Pitch LE to LE distance between two adjacent blades. Turningangle deflection angle between the LE and TE camber lines. Stagger angleangle between the blade chord and the turbine radius. Incidence angleangle between the incoming wind and the camber line. Solidity ratio ofchord divided by pitch.

Velocity vectors as U_(t1), U_(r1), and U₁. U_(r1) being the velocityradial component along R₁, R₁ being the radius to the outer diameter ofthe stator blades and U_(t2) being the rotational speed vector along R₂,R₂ being the radius to the outer diameter of the rotor blades. Theturned trailing edges of the stator blades generate the pre-swirlvelocity of U_(t1). It also reduces the passage area more than a radialtrailing edge and hence accelerates the flow prior to striking the VAWT.Indices 1 and 2 on the vectors indicate blade inlet and outlet location,respectively. V is the rotating velocity of the blade and varies withthe radius, W is the relative flow velocity observed on the rotatingframe with the turbine, and U is the absolute velocity observed on theground. Increased mass flow rate, rotating velocity, and flow turningwill increase the turbine work output. This working principle is thesame as that of aircraft engine turbines.

The stator blade is oriented such that the sufficient stagger angle 58exists between a first line 62 and a second line 50, the first line 62passing perpendicular from the LE of the stator blade to the center ofvertical axis 60, the second line 50 passing from the LE 16 of thestator blade to the TE 18 of the stator blade. In order to be efficient,the stagger angle of the stator and rotor are computed such that theangle of the relative velocity (in the rotor frame of reference) doesnot exceed the stall angle of the rotor. This stall angle is determinedto be between −50° and 50° for the current embodiments of the invention.Take FIG. 4 as example, the stagger angle on the left of the verticalradial line is defined as negative, on the right is defined as positive.

The stator blades are configured to allow a prevailing wind to passbetween any two adjacent stator blades 12. The stator blades constructedand arranged to accelerate fluid flow prior to contacting the rotatablerotor blades 14. One aspect of the instant invention includes aplurality of adjacent stator blades, each stator blade arranged topermit passage of a fluid flow between an adjacent stator blades andfurther each stator blade arranged for accelerating the fluid flow, atleast one rotor blade 14 arranged to be rotated by the accelerated fluidflow.

The work extracted from the wind by the rotor strongly depends on theangular velocity (RPM) but also the incidence angle at which the windcoming out of the stator strikes the rotor leading edge. The preferredincidence angle is about two degrees (2°). In turns, this angle alsodepends on the angular velocity. In order to do these calculations, twomajor inputs are needed: incoming wind speed and RPM. For all turbines,HAWT and VAWT, the single formula: P=½ρAKV³ holds. This is Power equalto the product of density (ρ), frontal area (A) and wind speed (V). Theefficiency coefficient (K) is to be determined and can change withvarious wind speed.

Adjacent stator blades 12 accept prevailing wind there between, thegeometry and arrangement of each stator blade causing an acceleration ofthe prevailing wind; the adjacent stator blades direct the acceleratedfluid flow into rotor blades for rotation. The rotor blades 14 may beadjusted to change the pitch of the rotor blades to accommodate typicalwinds at the installed location.

It is to be understood that while a certain form of the invention isillustrated, it is not to be limited to the specific form or arrangementherein described and shown. It will be apparent to those skilled in theart that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to whatis shown and described in the specification and any drawings/figuresincluded herein.

One skilled in the art will readily appreciate that the presentinvention is well adapted to carry out the objectives and obtain theends and advantages mentioned, as well as those inherent therein. Theembodiments, methods, procedures and techniques described herein arepresently representative of the preferred embodiments, are intended tobe exemplary and are not intended as limitations on the scope. Changestherein and other uses will occur to those skilled in the art which areencompassed within the spirit of the invention and are defined by thescope of the appended claims. Although the invention has been describedin connection with specific preferred embodiments, it should beunderstood that the invention as claimed should not be unduly limited tosuch specific embodiments. Indeed, various modifications of thedescribed modes for carrying out the invention which are obvious tothose skilled in the art are intended to be within the scope of thefollowing claims.

What is claimed is:
 1. A turbine securable to a generator andpositionable in a fluid flow for converting kinetic energy intomechanical energy for use in electrical power generation, said turbinecomprising: a stator section formed from a plurality of geometricallyshaped and vertically positioned stator blades having a leading edge anda trailing edge with an upper surface shaped convexly from said statorblade leading edge to said stator blade trailing edge and a pressuresurface shaped concavely from said leading edge to said trailing edge,each said stator blade having an upper end secured to a fixed stator topplate and a lower end secured to a fixed stator bottom plate, eachstator blade oriented to provide a stagger angle wherein said uppersurface of said stator blade is constructed and arranged to generate apre-swirl of the fluid flow to guide the fluid flow to a tangentialdirection in the direction of rotor rotation to accelerate the fluidflow, each said stator blade oriented such that a sufficient staggerangle exists between a first line passing perpendicular from the leadingedge of said stator blade to the center of the vertical axis and asecond line passing from said leading edge of the stator blade to thetrailing edge of said stator blade wherein the angle of relativevelocity does not exceed the stall angle of said stator blade; a rotorsection formed from a plurality of geometrically shaped vertical bladeshaving a leading edge and a trailing edge with an upper surface shapedconvexly from said rotor blade leading edge to said rotor blade trailingedge and a lower surface shaped concavely from said rotor blade leadingedge to said rotor blade trailing edge, each rotor blade having an upperend secured to a rotatable top plate and a lower end secured to arotatable lower plate constructed and arranged to rotate about alongitudinal axis within said stator section; wherein the fluid flow isaccelerated prior to striking a rotor whereby fluid directed past twoadjacent stator blades is accelerated for use in enhanced rotation ofsaid rotor section.
 2. The turbine according to claim 1 wherein eachsaid stator blade is oriented at a sufficient stagger angle so that anangle of relative velocity does not exceed the stall angle of a rotorblade.
 3. The wind turbine according to claim 1 wherein each said rotorblade has an incidence angle of about two degrees (2°).
 4. The turbineaccording to claim 1 wherein pitch of said rotor blades is adjustable.5. The turbine according to claim 1 wherein pitch of said rotor bladesis adjustable.